<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- This file documents the GNU Assembler "as".

Copyright (C) 1991-2016 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled "GNU Free Documentation License".
 -->
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Using as: Z80 Opcodes</title>

<meta name="description" content="Using as: Z80 Opcodes">
<meta name="keywords" content="Using as: Z80 Opcodes">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="AS-Index.html#AS-Index" rel="index" title="AS Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Z80_002dDependent.html#Z80_002dDependent" rel="up" title="Z80-Dependent">
<link href="Z8000_002dDependent.html#Z8000_002dDependent" rel="next" title="Z8000-Dependent">
<link href="Z80-Directives.html#Z80-Directives" rel="prev" title="Z80 Directives">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Z80-Opcodes"></a>
<div class="header">
<p>
Previous: <a href="Z80-Directives.html#Z80-Directives" accesskey="p" rel="prev">Z80 Directives</a>, Up: <a href="Z80_002dDependent.html#Z80_002dDependent" accesskey="u" rel="up">Z80-Dependent</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Opcodes-21"></a>
<h4 class="subsection">9.53.5 Opcodes</h4>
<p>In line with common practice, Z80 mnemonics are used for both the Z80 and
the R800.
</p>
<p>In many instructions it is possible to use one of the half index
registers (&lsquo;<samp>ixl</samp>&rsquo;,&lsquo;<samp>ixh</samp>&rsquo;,&lsquo;<samp>iyl</samp>&rsquo;,&lsquo;<samp>iyh</samp>&rsquo;) in stead of an
8-bit general purpose register. This yields instructions that are
documented on the R800 and undocumented on the Z80.
Similarly <code>in f,(c)</code> is documented on the R800 and undocumented on
the Z80.
</p>
<p>The assembler also supports the following undocumented Z80-instructions,
that have not been adopted in the R800 instruction set:
</p><dl compact="compact">
<dt><code>out (c),0</code></dt>
<dd><p>Sends zero to the port pointed to by register c.
</p>
</dd>
<dt><code>sli <var>m</var></code></dt>
<dd><p>Equivalent to <code><var>m</var> = (<var>m</var>&lt;&lt;1)+1</code>, the operand <var>m</var> can
be any operand that is valid for &lsquo;<samp>sla</samp>&rsquo;. One can use &lsquo;<samp>sll</samp>&rsquo; as a
synonym for &lsquo;<samp>sli</samp>&rsquo;.
</p>
</dd>
<dt><code><var>op</var> (ix+<var>d</var>), <var>r</var></code></dt>
<dd><p>This is equivalent to
</p>
<div class="example">
<pre class="example">ld <var>r</var>, (ix+<var>d</var>)
<var>opc</var> <var>r</var>
ld (ix+<var>d</var>), <var>r</var>
</pre></div>

<p>The operation &lsquo;<samp><var>opc</var></samp>&rsquo; may be any of &lsquo;<samp>res <var>b</var>,</samp>&rsquo;,
&lsquo;<samp>set <var>b</var>,</samp>&rsquo;, &lsquo;<samp>rl</samp>&rsquo;, &lsquo;<samp>rlc</samp>&rsquo;, &lsquo;<samp>rr</samp>&rsquo;, &lsquo;<samp>rrc</samp>&rsquo;,
&lsquo;<samp>sla</samp>&rsquo;, &lsquo;<samp>sli</samp>&rsquo;, &lsquo;<samp>sra</samp>&rsquo; and &lsquo;<samp>srl</samp>&rsquo;, and the register
&lsquo;<samp><var>r</var></samp>&rsquo; may be any of &lsquo;<samp>a</samp>&rsquo;, &lsquo;<samp>b</samp>&rsquo;, &lsquo;<samp>c</samp>&rsquo;, &lsquo;<samp>d</samp>&rsquo;,
&lsquo;<samp>e</samp>&rsquo;, &lsquo;<samp>h</samp>&rsquo; and &lsquo;<samp>l</samp>&rsquo;.
</p>
</dd>
<dt><code><var>opc</var> (iy+<var>d</var>), <var>r</var></code></dt>
<dd><p>As above, but with &lsquo;<samp>iy</samp>&rsquo; instead of &lsquo;<samp>ix</samp>&rsquo;.
</p></dd>
</dl>

<p>The web site at <a href="http://www.z80.info">http://www.z80.info</a> is a good starting place to
find more information on programming the Z80.
</p>




</body>
</html>
